The present invention relates to an ink jet system printer of the charge amplitude controlling type and, more particularly, to an improvement on a deflection means in an ink jet system printer.
Undesirable dust such as thread drifting in the air will be captured in a deflection section in an ink jet system printer because of a high voltage electric field established by deflection electrodes. This causes printing distortion since non-uniformity will be created in the electric field by the dust captured in the deflection section and/or travelling ink droplets emitted from a nozzle will come into collision with the dust captured in the deflection section.
When the ink droplets impinge upon a recording paper at very high speeds, ink fog is unavoidably diffused in various directions. The ink fog bears the same charge as the ink droplet from which it originates and, therefore, the ink fog tends to be attracted toward one of the deflection electrodes which is biased with opposite polarities from the ink fog. Hence, the ink fog becomes attached to the deflection electrode, which may cause the system to operate erroneously or break down, since the insulation of the system can not be maintained.
In the conventional plate shaped deflection electrodes, the above-mentioned dust captured in the deflection section and the ink fog attached to the deflection electrodes could not be removed, since the conventional deflection plates are stationary fixed to the system of the printer. Moreover, a large number of dust will be captured in the deflection section of the conventional system, because the deflection plates are provided to extend across the whole printing region in the conventional system.